Two, trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speeds is:

A. 2 : 3
B. 4 : 3
C. 6 : 7
D. 9 : 16

• Let the slower train have speed of 1 unit and faster train a speed of
  r units of speed.
  
  Let t = time to when the trains meet.
  
  rt 1t
  Howrah|-----------------------|----------| Patna
  meet
  
  They meet rt units from Howrah and 1t units from Patna
  
  For the second part of the journey the fast train at speed r has 1t
  unit of distance and 9 hours to do it
  
  So 1t/r = 9
  
  Slow train has rt units of distance at speed of 1 unit and 16 hours
  to do it.
  
  rt/1 = 16
  
  So rt/1 16
  ----- = ---- giving r^2 = 16/9
  1t/r 9
  r = 4/3
• 12 years agoHelpfull: Yes(7) No(2)
• Formula:
  if two trains or bodies start at same time from point A and B towards each other and after crossing they take a and b seconds in reaching B and A resp. then
  (A's speed): (B's speed)= (square root of a : square root of b)
  therefore answer is square root of 16 : square root of 9
  = 4:3
• 11 years agoHelpfull: Yes(4) No(1)
• Let us name the trains as A and B. Then,
  
  (A's speed) : (B's speed) = b : a = 16 : 9 = 4 : 3.
• 9 years agoHelpfull: Yes(2) No(0)
• root b : root a
  root 16 : root 9
  4 : 3
  option is b
• 4 years agoHelpfull: Yes(0) No(0)